1-Cyclopropyl-6-monofluoro- and 6,8-difluoro-1,4-dihydro-4-oxo-quinoline-3carboxylic acids having a piperazino or an N-methylpiperazino group at the 7-position are known from European Patent Publication No. 78362, German Offenlegungschrift No. 3318145 and Belgian Patent No. 899,399. Similarly the 8-chloro-1-cyclopropyl-6-fluoro-1,4-dihydro-4-oxo-quinoline-3-carboxylic acids with piperazinyl side chains at the 7-position are described in European Patent Publication No. 167,763. The compounds are described as broad spectrum antibacterial agents.
5-Amino-1-ethyl-6,8-difluoro-1,4-dihydro-4-oxo7-[1-piperazinyl]-3-quinoline carboxylic acid is described in Japanese Patent Publication No. 58:174,367. Copending U.S. application Ser. No. 770,897 of Aug. 30, 1985, describes a group of 5-amino-1-cyclopropyl-6,8-difluoroquinolones as broad spectrum antibacterial agents. The amino substituents at the seven-position are limited to pyrrolidines and spiroamines.
It was thus surprising and unexpected to discover that the heretofore never described 7-piperazine derivatives of 5-amino- and 5-hydroxy -1-cyclopropylquinoline-r naphthyridine-3-carboxylic acids of the present invention have not only good broad spectrum antibacterial activity in general but especially better activity against Pseudomonas aeruginosa, an important and hard to kill bacteria in antibiotic therapy.